#!/bin/bash
#
# Copyright (c) 2019, Alliance for Open Media. All rights reserved
#
# This source code is subject to the terms of the BSD 2 Clause License and
# the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
# was not distributed with this source code in the LICENSE file, you can
# obtain it at www.aomedia.org/license/software. If the Alliance for Open
# Media Patent License 1.0 was not distributed with this source code in the
# PATENTS file, you can obtain it at www.aomedia.org/license/patent.
#
###############################################################################
# Fuzzer for libaom decoder.
# ==========================
# Requirements
# ---------------------
# Clang6.0 or above (must support -fsanitize=fuzzer)
#
# References:
# ---------------------
# http://llvm.org/docs/LibFuzzer.html
# https://github.com/google/oss-fuzz
#
# Steps to build / run
# ---------------------

set -eu

# Have a copy of AOM and a build directory ready.
if [[ $# -ne 2 ]]; then
  echo "Pass in the AOM source tree as first argument, and a build directory "
  echo "as the second argument. The AOM source tree can be obtained via: "
  echo "  git clone https://aomedia.googlesource.com/aom"
  exit 2
fi
if [[ -z "$CC" ]]; then
  echo "Set the CC environment variable to point to your C compiler."
  exit 2
fi
if [[ -z "$CXX" ]]; then
  echo "Set the CXX environment variable to point to your C++ compiler."
  exit 2
fi

AOM_DIR=$1
BUILD_DIR=$2
# Run CMake with address sanitizer enabled and build the codec.
# Enable DO_RANGE_CHECK_CLAMP to suppress the noise of integer overflows
# in the transform functions. Also set memory limits.
EXTRA_C_FLAGS='-DDO_RANGE_CHECK_CLAMP=1 -DAOM_MAX_ALLOCABLE_MEMORY=1073741824'
cd "${BUILD_DIR}"
cmake "${AOM_DIR}" -DCMAKE_BUILD_TYPE=RelWithDebInfo -DCONFIG_PIC=1 \
  -DCONFIG_SCALABILITY=0 -DCONFIG_LOWBITDEPTH=1 -DCONFIG_AV1_ENCODER=0 \
  -DENABLE_EXAMPLES=0 -DENABLE_DOCS=0 -DENABLE_TESTS=0 -DCONFIG_SIZE_LIMIT=1 \
  -DDECODE_HEIGHT_LIMIT=12288 -DDECODE_WIDTH_LIMIT=12288 \
  -DAOM_EXTRA_C_FLAGS="${EXTRA_C_FLAGS}" \
  -DAOM_EXTRA_CXX_FLAGS="${EXTRA_C_FLAGS}" -DSANITIZE=address

# Build the codec.
make -j$(nproc)

# Build some libaom utils that are not part of the core lib.
$CC -std=c99 -c -I${AOM_DIR} -I${BUILD_DIR} \
  ${AOM_DIR}/common/ivfdec.c -o ${BUILD_DIR}/ivfdec.o

$CC -std=c99 -c -I${AOM_DIR} -I${BUILD_DIR} \
  ${AOM_DIR}/common/tools_common.c -o ${BUILD_DIR}/tools_common.o

# Build the av1 fuzzer
$CXX -std=c++11 -DDECODER=av1 -I${AOM_DIR} -I${BUILD_DIR} \
    -fsanitize=fuzzer -Wl,--start-group \
    ${AOM_DIR}/examples/av1_dec_fuzzer.cc -o ${BUILD_DIR}/av1_dec_fuzzer \
    ${BUILD_DIR}/libaom.a ${BUILD_DIR}/ivfdec.o ${BUILD_DIR}/tools_common.o \
    -Wl,--end-group

echo "Fuzzer built at ${BUILD_DIR}/av1_dec_fuzzer."
echo "Create a corpus directory, copy IVF files in there, and run:"
echo "  av1_dec_fuzzer CORPUS_DIR"